1. Field of the Invention
The present invention relates to a technique for performing X-ray photography.
2. Description of the Related Art
A conventionally existing X-ray image diagnosis apparatus includes the following components:                an X-ray generation unit to irradiate X-rays        an X-ray detection unit placed to face the X-ray generation unit        a bed which is provided between the X-ray generation unit and the X-ray detection unit and on which an object is placed        a holding unit to hold the X-ray generation unit, X-ray detection unit, and bed and change their positions        an image processing unit to process image data read out from the X-ray detection unit        an operation unit to input X-ray irradiation condition settings, an instruction to start irradiation, information of an object, and the like        a system controller to perform operation control on each component described above        
When a doctor or technician who is an operator inputs X-ray irradiation condition settings and various kinds of operation instructions such as an instruction to start irradiation, the operation instruction information is communicated to the system controller. The system controller performs position adjustment for the X-ray generation unit, X-ray detection unit, and bed, starting and stopping of irradiation of X-rays, starting and stopping of image reading from the X-ray detection unit, and the like by sending control instructions to the respective units described above based on the above operation instruction information, thereby performing X-ray photography.
In this case, the operation unit may be placed in a medical room in which X-ray irradiation is performed or in an operation room different from the medical room. Alternatively, such operation units may be placed in both the medical room and the operation room. Such operation unit is connected to the system controller via a cable.
In general, various kinds of operation instructions are input to the X-ray image diagnosis apparatus via this operation unit. Conventionally, the X-ray image diagnosis apparatus is provided with an emergency stop button or the like in a system different from that of the operation unit. The operator presses such an emergency stop button in the event of a contingency, e.g., failure to communicate operation instruction information due to some cause such as disconnection or breakage of the cable which connects the operation unit to the system controller at the time of X-ray irradiation. That is, this button is provided for the safety of patients.
For example, patent reference 1 (Japanese Patent No. 2927206 (Japanese Patent Laid-Open No. 8-299317)) discloses a technique for monitoring a communication abnormality between devices constituting the X-ray image diagnosis apparatus. Patent reference 1 discloses an X-ray image diagnosis apparatus which includes a function of monitoring a communication abnormality between devices constituting the X-ray image diagnosis apparatus and specifying whether the abnormality resides in the cable connecting the respective devices or in each device itself.
The conventional technique, however, has the following problem. That is, when the operator cannot communicate operation instruction information associated with irradiation via the operation unit during X-ray irradiation, he/she can only perform operation like stopping irradiation by pressing the emergency stop button provided in a different system.
In addition, if the operator cannot communicate operation instruction information associated with irradiation, he/she cannot change any X-ray irradiation conditions. Irradiation is therefore continued under the irradiation conditions set immediately before the failure to communicate information. This poses a serious problem when X-ray photography must be continued during a surgical operation. If, for example, a failure to communicate operation instruction information occurs while a high dose of X-ray irradiation is temporarily set, photography is continued under the high dose of X-ray irradiation. This may irradiate the patient with an excessive dose of X-rays.